Y201-W Technical Manual

Y201-W Specification

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Contents

1. Overview
2. Default Settings
3. Quick Start
4. Wi-Fi and Serial Working Mechanism
5. Socket and Protocol Configuration
6. Additional Functions
7. AT Command Conventions and Common Commands
8. Troubleshooting

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1. Overview

Y201-W provides bidirectional transparent transmission between dual serial ports and Wi-Fi. Each serial port can be configured with Socket A and Socket B, supports TCP, UDP, HTTP, and MQTT, and can perform Modbus RTU to Modbus TCP conversion through the Modbus gateway.

The device supports two configuration entry points:

• Web UI, recommended for daily configuration and maintenance
• AT Commands, through serial AT or network AT

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2. Default Settings

Item	Default
Web Management IP, AP mode	192.168.4.1
Web Username	admin
Web Password	admin
Wi-Fi Mode	AP+STA
Serial Baud Rate	115200
Serial Format	8 / 1 / NONE
Socket Enable	Only serial port 1, Socket A enabled by default
Registration Packet	OFF
Heartbeat Packet	OFF
LAN Discovery Port	8168
LAN Discovery Keyword	HuayunIOT
Reboot on No Data	1440 min, 24 hours

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3. Quick Start

3.1 Hardware Connection

1. Connect the device to the PC or field controller with the serial cable.
2. Power on the device.
3. If default parameters must be restored, hold the Reset button for 3 to 5 s.

3.2 Log In to the Web UI

1. Connect to the device hotspot HY-W202.
2. Open 192.168.4.1 in a browser.
3. Log in with admin/admin.

3.3 TCP Server Quick Verification

1. On the Port 1 page, set Socket A to TCPServer and set the port to 6666.
2. Save and reboot the device.
3. On the PC, connect a TCP client to 192.168.4.1:6666.
4. Open the serial port tool with 115200/8/1/NONE.
5. Send and receive test data to verify bidirectional transparent transmission.

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4. Wi-Fi and Serial Working Mechanism

4.1 Wi-Fi Modes

Mode	Description
AP	The device provides a hotspot and terminals connect to the device
STA	The device joins an existing router or hotspot
AP+STA	The device provides a hotspot while joining an existing router, default

Notes:

• AP mode does not support hotspot scanning.
• AP+STA reduces wireless performance compared with single-mode operation.
• The channel affects 2.4 GHz / 5 GHz operation: channels 1 to 13 are 2.4 GHz, channels 36 to 165 are 5 GHz.

4.2 Serial Modes

Each serial port supports two modes:

• Transparent Mode, default: Serial data is forwarded to the Socket
• AT Mode: Serial data is handled as AT commands

Recommended sequence for entering AT mode:

1. Send +++
2. Wait about 500 ms, less than 3 s
3. Send a
4. Enter AT mode after receiving +ok

Exit AT mode by sending AT+EXIT or by rebooting the device.

4.3 Packetization

Transmission is triggered when either condition is met:

• Length trigger: length >= packet length, range 8 to 1460
• Interval trigger: inter-character gap >= packet interval, range 0 to 1000 ms

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5. Socket and Protocol Configuration

5.1 Socket Architecture

• Each serial port supports Socket A plus Socket B.
• When both channels are enabled, serial uplink data is duplicated and sent to both Sockets.
• Downlink data from both Sockets is merged onto the same serial output.

5.2 TCP Client and TCP Server

• TCP Client: Connects automatically after the device gets an IP address and retries every 1 s on failure
• TCP Server: Supports up to 8 concurrent clients on one port and disconnects the earliest client if the limit is exceeded

Examples:

AT+SOCKEN2B=ON
AT+SOCK2B=TCPC,192.168.1.16,7788
AT+REBOOT

AT+SOCKEN1A=ON
AT+SOCK1A=TCPS,192.168.1.16,7788
AT+REBOOT

5.3 UDP Client and UDP Server

• UDP Client: Uses a fixed target address and a fixed local port is recommended
• UDP Server: Receives data from multiple clients and sends to the most recently active one

Examples:

AT+SOCKEN1B=ON
AT+SOCK1B=UDPC,192.168.1.16,7788,5678
AT+REBOOT

AT+SOCKEN1B=ON
AT+SOCK1B=UDPS,192.168.1.16,7788
AT+REBOOT

5.4 HTTP Client

Supports GET / POST / AUTO with HTTP 1.0 / 1.1:

AT+SOCK1A=HTPC,www.rt-thread.com,80
AT+HTPHD1=Connection:keep-alive
AT+HTPREQ1=GET
AT+REBOOT

AT+SOCK1A=HTPC,www.rt-thread.com,80
AT+HTPURL1=/service/echo
AT+HTPHD1=Connection:keep-alive
AT+HTPREQ1=POST
AT+REBOOT

5.5 MQTT

MQTT works as a transparent-like mechanism. The device handles subscribe and publish actions, while the terminal side only needs to process the payload.

Core commands:

• AT+MQCONFn: Connection parameters, version, clean session, keepalive
• AT+MQAUTHn: Authentication, ID, username, password
• AT+MQSUBn: Subscribe enable, topic, QoS
• AT+MQPUBn: Publish enable, topic, QoS, retain
• AT+MQWILLn: Last will message
• AT+MQMDn: Mode selection, STD or ALI

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6. Additional Functions

6.1 Heartbeat Packet

• AT+HEARTMDn: OFF / UART / NET
• AT+HEARTTMn: 1 to 86400 s, default 60
• AT+HEARTDATn: Heartbeat content, HEX, 2 to 64 bytes

Notes:

• Network heartbeat only supports TCP and UDP client modes.
• Heartbeats pause while the device is in AT mode.

6.2 Registration Packet

• AT+REGTPn: MAC / CUS
• AT+REGMDn: OFF / FIRST / EVERY / ALL
• AT+REGDATn: Custom content, HEX, 2 to 64 bytes

6.3 LAN Discovery and Network AT

• Broadcast the keyword HuayunIOT to UDP port 8168 to discover the device.
• Network AT can be sent directly within 1 minute after discovery.

Related commands:

• AT+SEARCH=<port>,<key>
• AT+PING=<addr>

6.4 Firmware Upgrade

• HTTP upgrade: AT+DOWNLOAD=host:port/path.bin, returns OK if the download succeeds and requires manual reboot to apply
• Web upgrade: upgrade from the Web system page

6.5 Exception Handling

• AT+SOCKRTO=<time> sets reboot on network inactivity; 0 disables it
• Default value is 1440, which equals 24 hours

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7. AT Command Conventions and Common Commands

7.1 Command Rules

• Commands start with AT+ and end with \r\n
• Send one command at a time; the maximum command length is 256 bytes
• Parameters are saved automatically after being set and take effect after reboot
• Wait for the response to the previous command before sending the next one

7.2 Quick Commands

Command	Function
AT+LIST	List supported commands
AT+EXIT	Exit AT mode
AT+REBOOT	Reboot device
AT+RSTCFG	Restore backup parameters and reboot
AT+MAC	Query MAC address
AT+VER	Query firmware version
AT+DEVINFO	Query device information

7.3 Common Error Codes

Error Code	Meaning
ARGS	Invalid parameter
ARGC	Wrong number of parameters
CMD_UNKNOWN	Unknown command
CMD_FORMAT	Invalid format
CMD_LENGTH	Command too long
DEV_MEMORY	Memory error
DEV_SAVE	Save failed

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8. Troubleshooting

Symptom	Possible Cause	Recommended Action
Cannot access Web UI	The subnet does not match or the device is not in AP mode	Reset the device, connect to HY-W202, and access 192.168.4.1
TCP connection cannot be established	Wrong address or port, firewall blocking	Check Socket settings and open the required port
UDP can receive but not send	Local port not fixed or peer has not sent data	Set a fixed local port in UDP client mode and send one packet first
Serial communication is abnormal	Serial parameters do not match	Align baud rate, data bits, parity, and stop bits
Heartbeat is not sent	Mode mismatch or the device is still in AT mode	Check HEARTMDn, connection state, and exit AT mode
Registration packet is not reported	Registration mode is disabled	Check REGTPn, REGMDn, and REGDATn
Parameters are lost after reboot	Parameters were not backed up or rebooted correctly	Reboot after configuration and use BKCFG when needed
Frequent automatic reboot	SOCKRTO triggered	Adjust AT+SOCKRTO or disable the feature

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• Manufacturer: Hunan YenGear Tech Co., Ltd.
• Address: Room 21014, Building 1, Fudi Xingguang Tiandi, Yingxin Road, Yuhua District, Changsha, Hunan, China
• Email: hi@yengear.com
• Website: www.yengear.com